Patent GB-1233918-A (GB)
IPC: D04H1/64
Filed: 1968-08-08
Abstract: 1,233,918. Imitation leather. TORAY INDUSTRIES Inc. 8 Aug., 1968 [17 April, 1968], No. 38011/68. Heading B2E. An imitation leather is produced by applying a thermoplastic polymer to the surface of a non-woven fibrous sheet material from which fibres project slightly giving a fluffy appearance to the surface and contacting the surface with a smooth surface heated to a temperature not lower than the glass transition point of fibres constituting the fibrous sheet material but not not higher than the melting point of the polymer to smooth the surface of the sheet impregnating the fibrous sheet with a solution of a coagulatable binder, coating the polymerbearing surface of the fibrous sheet with a solution of a synthetic resin, and thereafter coagulating the binder and resin. Preferably the coating of synthetic resin is dissolved in a solvent which is the same as or compatible with the solvent of the binder solution and is applied to the fibrous sheet material while the binder solution is not substantially coagulated and then both the binder and the coating of synthetic resin are coagulated similtaneously. The fibrous sheet material may be composed of natural fibres, regenerated fibres, synthetic fibres or blends thereof and the fibres may be made into a sheet by a paper-making process or by carding, or by subjecting a web to chain stitch needling. The thermoplastic polymer can be natural rubber, synthetic rubber such as acrylonitrile-butadiene copolymer, synthetic polymer such as polyacrylic ester, polyvinyl chloride and polyvinyl alcohol, natural polymer such as starch and casein, cellulose derivatives such as carboxymethyl cellulose applied either as solution or emulsion by spraying, gravure coater and kissing coater. As the heated surface a hot press or cylinder roll may be used. Examples of binders and synthetic resins are thermoplastic resins, such as polyamides. polyvinyl chloride, polyacrylonitrile, synthetic rubbers such as a acrylonitrile-butadiene copolymer and styrene-butadiene copolymer, and polyurethane applied as a solution in a solvent which is a non-solvent for the fibres. The viscosity of the coating of such resin should be higher than that of the binder solution. Pigments such as carbon black, fillers such as precipitated calcium carbonate and cellulose powder or a plasticiser may be incorporated into the synthetic resin solution. The binder solution may be uniformly impregnated into an inner layer of the fibrous sheet material with the use of a squeezing machine, and subsequently the synthetic resin applied to the surface by means of a reverse roll coater or knife coater. The binder resin and coating synthetic resin may be coagulated by extraction of the solvent with a liquid such as water, or by extraction of the solvent by means of heating. The imitation leather may be embossed. A nitro-cellulose lacquer may be further applied. In one embodiment high molecular weight polymer which is in soluble in solvents for the binder resin and the synthetic resin and is soluble in the coagulating liquid is applied to a sheet material, the binder resin and coating synthetic resin are then applied and subsequently coagulated and/or water washed so that the high molecular weight polymer is dissolved and removed to prevent excessive bonding between the binder and the fibres and thereby to make a final product pliable. In the Examples a non-woven sheet of crimped polyester staple fibres punched with a needle loom, and a non-woven sheet of crimped nylon fibres punched with a needle loom are utilised.